It has been suggested that one route of estrogenic steroids' influence on mammary cancer is via the increased production of prolactin from the pituitary. We propose to extend our preliminary observations on estrogen effects on prolactin biosynthesis in the pituitary. In particular, we would like to continue studies on the messenger RNA for what appears to be a prolactin precursur. We would like to isolate the pre-prolactin mRNA from pituitary polysomes and characterize it. A comparison of the mRNA from a rat pituitary tumor line will be made with normal pituitary. We will try to determine whether the estrogen effect on prolactin synthesis involves mRNA synthesis or processing. Our ultimate goal is to determine how the cell genome in normal and neoplastic pituitary tissue is regulated by estrogenic hormones.